1. Field of the Invention
This invention relates to a self propelled gun.
2. Discussion of Prior Art
Mobility is a key factor in modern warfare and for any piece of artillery to play a valuable part on the battlefield it must be able rapidly to reach the scene of conflict, that is it must be able rapidly to be tactically deployed. Although there is a wide range of field artillery such as tanks, self propelled howitzers and guns, towed field howitzers and guns and self propelled mortars, each has its own weaknesses in rapid deployment scenarios.
Tanks, for example, are heavy (50-60 Tonnes), well armoured tracked vehicles with a turret mounted medium calibre gun (105-140 mm) which are generally used on line of sight, short range engagements. Although a single tank can be transported by the heaviest lift aircraft, such aircraft are restricted by the availability of suitable landing sites and therefore tanks can only be strategically deployed by air and have to be transported by ship, rail or under their own power to the scene of conflict which can be many thousands of kilometers from such a landing site. Furthermore whilst readily mobile once on the battlefield, they are incapable of carrying substantial amounts of ammunition.
Self propelled howitzers are heavy (30-60 Tonnes), relatively lightly armoured tracked vehicles with a medium calibre gun (typically 155 mm) which is often turret mounted. Generally this armament is deployed well behind the front line as an indirect fire weapon with barrel elevations of between xe2x88x925xc2x0 and 70xc2x0 and has a range of up to 40 kilometers. As with tanks transporting this type of armament by air is impractical and deployment to a conflict must rely on ships, trains or their own mobility.
Self propelled guns are medium weight multi-wheeled or tracked vehicles having a medium calibre gun mounted on the rear of the vehicle. To assist in absorbing some of the energy when the gun is fired it is known for them to include one or more deployable spades at the rear of the vehicle which is/are lowered into engagement with the ground before firing.
Field howitzers and guns weigh up to 10 Tonnes and are an unarmoured indirect fire weapon, with a calibre up to 155 mm and a range up to 30 km. They can also be employed in a direct fire mode. Although some designs can have an auxiliary power unit (APU) giving very limited mobility on the battlefield they are normally towed by a lorry to, and around, the battlefield. Whilst air transportable by a fixed wing aircraft or helicopter, they are reliant upon lorries which also have to be transported to the battlefield for supplying them with ammunition.
A self propelled mortar is a relatively heavy (25-30 tonnes) lightly armoured tracked vehicle with a large calibre (240 mm) mortar. Generally they are an indirect fire weapon which is used at high elevation angles (45xc2x0 to 80xc2x0) and has a range of 10 km or 18.0 km with rocket assistance. In contrast to other types of artillery described the barrel has a smooth bore (not rifled) and is not trunnion mounted. As with tanks and self propelled howitzers this type of armament is not practical to deploy by air.
The inventors have appreciated that a need exists therefore for an air transportable, high mobility, medium calibre self contained weapon. The present invention has arisen in an endeavour to provide a such a weapon which, in part at least, overcomes the limitation of the known guns.
According to the present invention a self propelled gun comprises: a vehicle possessing a source of primary power and a gun assembly, said gun assembly comprising a base; a cradle pivotally mounted to the base and a barrel slidably mounted to the cradle such as to be displaceable from a first to a second position as a consequence of the barrel recoiling on firing characterised in that the gun assembly is movably mounted to the vehicle such that in a first, xe2x80x9cmobilityxe2x80x9d, mode the gun assembly is free of any direct contact with the ground, and said barrel points in a first direction allowing said vehicle to be driven and a second, xe2x80x9cfiringxe2x80x9d, mode in which the gun assembly is deployed to a firing position in which the base moves towards and into engagement with the ground and wherein said barrel is deployable through an angle of elevation which differs from said first direction by at least ninety degrees.
A particular advantage of the self propelled gun of the present invention is that since the base is in contact with the ground during firing the effective height of the pivot about which the cradle and barrel are mounted, that is the height above the ground, is minimised which reduces the effect of overturning forces making the gun more stable in operation. In contrast to the known self propelled guns the vehicle of the present invention does not carry the full shock load during firing and this enables the use of a comparatively lighter weight vehicle having a standard suspension arrangement.
Advantageously the first direction is in a substantially horizontal forward direction such that when the gun assembly has been deployed to the xe2x80x9cfiringxe2x80x9d mode the barrel is directed in a direction which is vertical or substantially away from the vehicle. This provides the additional advantages that:
(i) the vehicle acts as a virtual trail leg in that it increases the mass inertia of the gun assembly and helps counter the overturning moment of the recoil force, especially when firing at low angles of barrel elevation thereby eliminating the need for a deployable spade or trail legs; and
(ii) since the barrel is directed away from the vehicle it is capable of operating through a large range of barrel elevations from a small angle of depression to a high angle of elevation without the vehicle obstructing the gun assembly.
Preferably the first direction is additionally substantially coincident with the axis of the vehicle and the barrel is swung vertically upwards during deployment. This allows the sides of the vehicle deck to be used for storage of a substantial number of shells and charges, crew accommodation and auxiliary equipment thereby enabling the self propelled gun to operate as a self contained unit.
Preferably the gun assembly is movably mounted to the vehicle by the base being pivotally attached to the vehicle by a pivot arrangement. In a particularly preferred arrangement the pivot arrangement is configured such that deployment of the base into engagement with the ground raises a part of the vehicle in proximity with the pivot arrangement away from the ground. This is particularly advantageous since a proportion of the vehicle""s weight bears down through the pivot arrangement onto the base to assist in holding the gun assembly securely in contact with the ground when the gun is positioned and fired.
The barrel can be of normal or extended length (long range). Advantageously the barrel is held in the second position, i.e. in a fully recoiled position, during the xe2x80x9cmobilityxe2x80x9d mode to reduce the overall length of the self propelled gun and any overhang of the barrel beyond the vehicle. This is particularly advantageous in that it assists in providing unobscured driver vision and is of additional benefit when the gun is being transported by air where space is at a premium. Thus, in practice, after the last round has been fired, the barrel is held in the fully recoiled position. Preferably the barrel is held in the second position when deploying the gun assembly from the xe2x80x9cmobilityxe2x80x9d to xe2x80x9cfiringxe2x80x9d mode and vice versa. This has the further advantage that the centre of gravity of the barrel is shifted towards the trunnion bearing thus reducing the out of balance of the gun assembly during deployment and/or stowage which reduces the duty on the means for deploying the gun assembly. This is especially so when deploying the gun assembly with the vehicle on, and disposed transversely to, an inclined surface.
In a particularly preferred embodiment the cradle is pivotally mounted about a bearing which is positioned beyond the maximum point of recoil of the barrel thereby minimising the bearing height whilst still enabling the barrel to be elevated to high angles of elevation.
Advantageously the base incorporates one or more spades, which conveniently comprises one or more rearwardly angled blades on the underside of the body, which is/are such as to dig into the ground during recoil thereby enhancing the transmission of the recoil forces to the ground.